[cogl/wip/hadess/automake-1.16] ci: Add Xvfb and run the tests under it

[Emmanuele Bassi <ebassi src gnome org>]

commit 38b997d31a3389849b68c0e8e284939091a60d93
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Jun 4 11:45:01 2020 +0100

    ci: Add Xvfb and run the tests under it

 .gitlab-ci.yml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index bd9da106..6dc0dc77 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -11,8 +11,9 @@ variables:
     gettext-devel
     libtool
     chrpath
-    pkgconfig(cairo)
     mesa-libEGL-devel
+    xorg-x11-server-Xvfb
+    pkgconfig(cairo)
     pkgconfig(gbm)
     pkgconfig(gdk-pixbuf-2.0)
     pkgconfig(gl)
@@ -39,6 +40,6 @@ build_stable:
   script:
     - CPPFLAGS='-D_FORTIFY_SOURCE=2' ./autogen.sh --disable-dependency-tracking --disable-gtk-doc
     - make
-    - make check
+    - xvfb-run -a -s "-screen 0 1024x768x24" make check
     - make install